Vehicle number on fitness

Hi, I bought a car from a person and all procedure has been done. Registration, insurance, NTA... Except for motor vehicle license( declaration). When I bought the car the number was a private number and now with the registration the vehicle is on its original number. But on the fitness certificate it still the private number and the expiration date is oct 2016. What should I do to change this to the original number? Should I need to pay for a new one? Please help me.. Thanks